curb-sdk (Python)

The enforcement point for tool calls — the thing a proxy fundamentally cannot do.

pip install curb-sdk

You need a running Curb control plane for this to do anything. The fastest way: docker compose -f docker-compose.release.yml up -d — see the quickstart.

from curb import Curb, PolicyViolation

curb = Curb(base_url="http://localhost:8090", api_key="dev-key")

@curb.guard_tool(name="delete_file", sensitivity="high")
def delete_file(path: str) -> None:
    os.remove(path)

with curb.run() as run_id:
    # Cost and loops are covered too if your LLM client points at the gateway:
    #   OpenAI(base_url="http://localhost:8080/v1", default_headers=curb.gateway_headers())
    curb.step()                 # enforces step_limit / time_limit
    try:
        delete_file("/tmp/x")   # ASK → held until a human clicks Approve
    except PolicyViolation as e:
        print("denied:", e, e.policy_id)

Behaviour that matters

• Fail-safe. If the control plane is unreachable, or an approval runs out of time, the default is to deny (fail_mode="closed"). Set fail_mode="open" when availability matters more than protection.
• run_id propagates automatically through contextvars, so nested tools never need it passed explicitly.

Tests

python -m venv .venv && .venv/bin/pip install -e ".[dev]"
.venv/bin/python -m pytest -q